1. Field of the Invention
The present invention relates to transparencies for aircraft and particularly relates to a transparency system used in a crew module for aircraft. Particularly, the present invention relates to an improved add-on reinforcement for the aft arch of a transparency system that is used to reinforce the aft arch and the windshields of the transparency system used in the crew module for the F-111 aircraft.
Present day F-111 aircraft are provided with a crew module that can be separated from the aircraft in case the aircraft is severly damaged to the point that it can no longer fly. The crew module forms part of the aircraft and is provided with a transparency system comprising a pair of windshields in the forward part of the crew module and a pair of pivotable canopies in the rear portion of the module. A curved aft arch attached to the crew module is provided to connect the aft portion of the transparent windshields thereto in order to provide a rigid reinforcement and support for the transparent windshields of the crew module. In the past, despite the strength provided by the aft arch to reinforce the transparency system, the aircraft industry was unable to obtain penetration resistance as high as 445 knots when objects such as 4 pound (1.8 kilogram) birds were impacted against the most critical portion of the windshield, namely the aft portion of the windshield in the vicinity of the aft arch.
It is a purpose of the present invention to improve the resistance of the windshields of the transparency system for a crew module to penetration by high speed aircraft colliding with flying objects without adding unduly to the overall weight of the aircraft.
Another purpose of the present invention is to modify existing aircraft that fail to provide adequate impact penetration resistance by a simple method of reinforcing the aft arch of the transparency system in such a manner that it is not necessary to remove the windshields from the transparency system during installation of an add-on reinforcement to the aft arch that provides the desired improvement in resistance to penetration by high speed objects.
2. Description of Patents of Interest
A novelty search was conducted for the presently claimed structure of an add-on reinforcement member for an aft arch assembly and its method of application to reinforce the aft arch assembly with minimum disruption of the installation of a transparency system containing the windshield reinforced by the aft arch assembly. No patents which would appear to show the subject structure or its method of installation were located. Patents of general interest showing windshield mountings were noted and reported as most pertinent. These patents include U.S. Pat. No. 2,258,724 to Wagner et al., which relates to fixation of window panes in aircraft, U.S. Pat. No. 2,293,656 to McClain, which relates to a transparent closure and mounting for aircraft, U.S. Pat. No. 2,414,705 to Ames, which relates to means for attaching thermoplastic sheet to other materials, U.S. Pat. No. 2,834,998 to Wilder, which relates to means for mounting a frangible expanse to a vibratile support, U.S. Pat. No. 2,939,186 to Morewood et al., which relates to an enclosure device such as an aircraft canopy and a mounting therefor, and U.S. Pat. No. 3,477,667 to Lock, which relates to windshields for supersonic aircraft provided with a movable transparent shield.